Those attempts were more about proving
2 stops isn't even often necessary with nature type photography
.

You've made this statement several times and I don't even know what it means.

These are the overall reference scenes I posted from my informal garden tests yesterday - from the middle of the day with bright sunshine - the light dosn't get much better here in the UK.

One was over 2 stops under, the other was 5 stops under. Granted, they're only dark corners of my garden - but they could equally be on a deer amongst trees, or a bird in foliage. Obviously, presented with 5 stop deficit in shutter speed, I'd up ISO a little for a better compromise, but saying that 2 stops of shutter speed is rarely needed doesn't even make sense.

126mm @ 1/160 - EXIF in the image - it's over 2 stops under in sunlight:

126mm @ 1/27 - EXIF in tact:

I think these would qualify as 'nature' shots. I think I'd find it very rare at 126mm that I could ever actually secure an optimal exposure - i.e. 1/750 @ ƒ6.4 (stopped for better IQ) and 100ISO. Your light in NZ must be quite something if you rarely need better than 2 stops at 126mm.